1. Field of the Invention
The invention relates generally to digital image processing and the display of digitally generated images. The invention relates more specifically to the problem of creating high-resolution animated images in real time.
2a. Copyright claims to disclosed Code-conversion Tables
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. In particular, this application includes listings of code conversion tables named: ITPCON, HVON, HV0ON, HV1ON, HV2ON, HV3ON. These code-conversion tables can be implemented by way of a computer program, microcode, in a ROM, and so forth. These code-conversion tables can also be implemented by way of combinatorial logic. Since implementations of the tables which are deemed to be "computer programs" are protectable under copyright law, copyrights not otherwise waived above in said code-conversion listings are reserved. This reservation includes the right to reproduce the code-conversion tables in the form of machine-executable computer programs.
2b. Cross Reference to Related Applications
This application is related to:
U.S. patent application Ser. No. 07/970,308 entitled AUDIO/VIDEO COMPUTER ARCHITECTURE, by inventors Mical et al., filed concurrently herewith, Attorney Docket No. MDIO4222;
U.S. patent application Ser. No. 07/970,274 entitled METHOD FOR GENERATING THREE DIMENSIONAL SOUND, by inventor David C. Platt, filed concurrently herewith, Attorney Docket No. MDIO4220;
U.S. patent application Ser. No. 07/970,278 entitled METHOD FOR CONTROLLING A SPRYTE RENDERING PROCESSOR, by inventors Mical et al., filed concurrently herewith, Attorney Docket No. MDIO3040;
U.S. patent application Ser. No. 07/970,289 entitled SPRYTE RENDERING SYSTEM WITH IMPROVED CORNER CALCULATING ENGINE AND IMPROVED POLYGON-PAINT ENGINE, by inventors Needle et al., filed concurrently herewith, Attorney Docket No. MDIO4232;
U.S. patent application Ser. No. 07/969,994 entitled METHOD AND APPARATUS FOR UPDATING A CLUT DURING HORIZONTAL BLANKING, by inventors Mical et al., filed concurrently herewith, Attorney Docket No. MDIO4250;
U.S. patent application Ser. No. 07/970,083 entitled IMPROVED METHOD AND APPARATUS FOR PROCESSING IMAGE DATA, by inventors Mical et al., filed concurrently herewith, now U.S. Pat. No. 5,572,235, issued on Nov. 5, 1996; and
U.S. patent application Ser. No. 07/970,151 entitled PLAYER BUS APPARATUS AND METHOD, by inventors Needle et al., filed concurrently herewith, Attorney Docket No. MDIO4270.
The related patent applications are all commonly assigned with the present application and are all incorporated herein by reference in their entirety.
3. Description of the Related Art
In recent years, the presentation and pre-presentation processing of visual imagery has shifted from what was primarily an analog electronic format to an essentially digital format.
Unique problems come to play in the digital processing of image data and the display of such image data. The more prominent problems include providing adequate storage capacity for digital image data and maintaining acceptable data throughput rates while using hardware of relatively low cost. In addition, there is the problem of creating a sense of realism in digitally generated imagery, particularly in animated imagery.
The visual realism of imagery generated by digital video game systems, simulators and the like can be enhanced by providing special effects such as moving sprites, real-time changes in shadowing and/or highlighting,, smoothing of contours and so forth.
Visual realism is further enhanced by increasing the apparent resolution of a displayed image so that it has a smooth photography-like quality rather than a grainy disjoined-blocks appearance of the type found in low-resolution computer-produced graphics of earlier years.
Although bit-mapped computer images originate as a matrix of discrete lit or unlit pixels, the human eye can be fooled into perceiving an image having the desired photography-like continuity if a matrix format comprised of independently-shaded (and/or independently colored) pixels is provided having dimensions of approximately 500-by-500 pixels or better at the point of display.
The VGA graphics standard, which is used in many present-day low-lost computer systems, approximates this effect with a display matrix having dimensions of 640-by-480 pixels. Standard-definition NTSC broadcast television also approximates this effect with a display technology that relies on interlaced fields with 525 lines per pair of fields and a horizontal scan bandwidth (analog) that is equivalent to approximately 500 RGB colored dots per line.
More advanced graphic display standards such as Super-VGA and High Definition Television (HDTV) rely on much higher resolutions, 1024-by-786 pixels for example. It is expected that display standards with even higher resolution numbers (e.g., 2048-by-2048) will emerge in the future.
As resolutions increase, the problem of providing adequate storage capacity for the corresponding digital image data becomes more acute. The problem of providing sufficient data processing throughput rates also becomes more acute. This is particularly so if the additional constraint of keeping hardware costs within acceptable price versus performance ranges comes in to play.
A display with 640-by-480 independent pixels (307,200 pixels total) calls for a video-speed memory unit (frame buffer) having at least 19 address bits or a corresponding 2.sup.19 independently-addressable data words (=512K words), where each data word stores a binary code representing the shading and/or color of an individual pixel. Each doubling of display resolution, say from 640-by-480 pixels to 1280-by-960 pixels, calls for a four-fold increase in storage capacity. This means an increase from 512K words to 2M words (two Megawords) in the given example. And in cases where parts or all of the 1280-by-960 display field have to be modified in real-time (to create a sense of animation), the four-fold increase of storage capacity calls for a corresponding four-fold increase in data processing bandwidth (image bits processed per second) as compared to what was needed for processing the 640-by-480 field.
The benefit versus cost ratio incurred by demands for more storage capacity and faster processing speed has to be questioned at some point. Perhaps the increase in performance is not worth the increase in system cost. On the other hand, it might be possible to create a perception of improved performance without the burden of increased cost.